This invention relates generally to equipment for processing particulate materials and more particularly to a steam injection housing for a vertical steam conditioning chamber.
Processing of particulate materials such as plastic pellets, feed grains, or other particles frequently requires treatment with steam to heat, moisturize, and possibly soften the particles for subsequent processing. In many cases, this treatment or steam conditioning is accomplished in a vertical chamber in which the steam flows upward in a counterflow direction to the downward flowing feed grains. Typically, steam is introduced at one or more points in the housing through a steam injection nozzle which is often no more than a perforated straight piece or curved piece of pipe mounted within the chamber and connected, through a steam inlet, to a steam manifold and source. In all cases, the form of the injection device is dictated by the geometry of the chamber in order to provide uniform exposure of the particles to the conditioning steam. Perforated pipe injectors, however, have at least one serious shortcoming. They are susceptible to being plugged by partially conditioned moist and soft particles. Another objection to such injectors is that the distribution of conditioning steam across the chamber is not uniform and that some of the particles are not completely conditioned as a result of this nonuniformity. Finally, because of their tubular shape, conventional steam injectors promote bridging of particles which jams the conditioning chamber.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.